The invention relates to a drive unit for a motor vehicle having an all-wheel drive which is designed, for example, for use in the agriculture and construction sectors and/or for civil and disaster protection tasks.
A motor vehicle that has a high off-road capability is known from U.S. Patent Document U.S. Pat. No. 3,331,464. For driving the motor vehicle, an internal-combustion engine is used, which is arranged between a front axle and a rear axle. The internal-combustion engine having a centrifugal clutch acts by means of a drive shaft extending transversely with respect to the longitudinal direction of the vehicle and an angle drive upon a first V-pulley set of a CVT transmission. Its second V-pulley set is connected with a transmission which, on the one side, is in an operative connection with the rear axle and, on the other side, is in an operative connection with the front axle, so that the motor vehicle has a four-wheel drive.
From U.S. Patent Document U.S. Pat. No. 2,915,133, a motor vehicle of the sports car or racing car type is known, which has an internal-combustion engine between the wheel axles. The internal-combustion engine installed close to a front axle has cylinder banks that are arranged in a V-shape and extend diagonally toward the right vehicle side. A crankshaft of the internal-combustion engine, which extends in the longitudinal direction of the motor vehicle, drives the front axle and the rear axle by way of transmissions.
German Patent Document DE 2 160 430 relates to an equipment carrier constructed in the style of a tractor. An internal-combustion engine drives the front wheels and the rear wheels. In this case, an internal-combustion engine is installed between a front axle and a rear axle, and a first cardan shaft connects the front axle with the rear axle. A second cardan shaft extends between a transmission interacting with the internal-combustion engine and the rear axle. For achieving a defined ground clearance of the equipment carrier, both cardan shafts extend laterally past an engine mount of the internal-combustion engine.
It is an object of the invention to provide a drive unit for a motor vehicle having an all-wheel drive, by means of which a motor vehicle can be used in a versatile manner. However, in this case, it should also be ensured that the internal-combustion engine and the transmission device with drive shafts for the wheels of driving axles of the drive unit, on the one hand, can be implemented at acceptable expenditures and, on the other hand, are distinguished by good functioning.
According to the invention, this and other objects are achieved by a drive unit for a motor vehicle having an all-wheel drive, the drive unit being situated between a first wheel axle and a second wheel axle and having an internal-combustion engine with a crankshaft system comprising at least one horizontally oriented crankshaft. The crankshaft acts upon a continuously variable transmission system which drives wheels of the first wheel axle and of the second wheel axle. The crankshaft of the crankshaft system is caused to rotate by at least one piston of the internal-combustion engine and interacts with a first set of V-pulleys of the transmission system. The first set of V-pulleys, by way of a first drive shaft, is connected with a first differential of the first wheel axle. The first set of V-pulleys, by way of an endless member, is in an operative connection with a second set of V-pulleys which, with the interposition of a second drive shaft, influences a second differential of the second wheel axle.
The principal advantages achieved by the invention are that the interaction of the crankshaft of the crankshaft system of the internal-combustion engine with the first set of V-pulleys and its connection with the first drive shaft as well as the drive of the second set of V-pulleys by the first set of V-pulleys as well as the influencing of the second drive shaft by the second continuously variable transmission create exemplary technical prerequisites for the drive unit. On the one hand, these are distinguished by a simple implementability. On the other hand, a motor vehicle designed in such a fashion provides excellent services for use in the agriculture and construction sectors but also for civil and disaster protection tasks.
This all-wheel concept is supported by the internal-combustion engine having the crankshaft system comprising two crankshafts, which crankshafts rotate in opposite directions by way of synchronization gears. This method of construction results in excellent operating characteristics of the internal-combustion engine, specifically with respect to smooth running, consumption and stability. In a constructively skillful manner, it is achieved that the output of the crankshaft system toward the first set of V-pulleys takes place from the first end region of the crankshaft system, and that, in the second end region of the crankshaft system, the crankshafts are equipped with flywheels. It should be stressed in this context that a power take-off shaft for the drive of accessories is provided on at least one crankshaft.
It is useful that the second drive shaft extends below a cylinder crankcase of the internal-combustion engine, and that the internal-combusting engine extends diagonally with respect to a horizontal line for guiding the second drive shaft past the cylinder crankcase.
It is a sophisticated construction that a clutch is connected into a driving shaft between the first end region of the crankshaft system and the first set of V-pulleys. This clutch may be a shifting clutch, a centrifugal clutch or the like. Finally, it is creatively advantageous that the axes rotation of the crankshafts as well as of the first and second drive shafts are oriented in the longitudinal direction of the vehicle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.